[Ballerina (John Wick)] Why would the Ruska Roma actually take this threat seriously?

When Eve goes after the people who killed her father when she was a child, they're threatening the Ruska Roma that trained her that there would be "war" if they don't stop her.

And the Ruska Roma are basically treating this rival organization as a serious threat, with which they wouldn't want to break truce under any circumstances whatsoever.

But the thing is: they essentially just proved, by the mere act of making this threat and their apparent *need* to make it, in the first place, that they cannot even take out *a single rogue agent* of the Ruska Roma – without any support or allies – on their own.

So why the hell should they be taken seriously as a threat to the entire organization?